PREDICTING SWITCHED-BIAS RESPONSE FROM STEADY-STATE IRRADIATIONS

A new semi-empirical model of radiation-induced charge neutralization is presented. We combine this model with 12 heuristic guidelines derived from studies of oxide- and interface-trap charge (ΔVot and ΔVit) buildup and annealing to develop a method to predict MOS switched-bias response from steady-state irradiations, with no free parameters. For n-channel MOS devices, predictions of ΔVot, ΔVit, and mobility degradation differ from experimental values through irradiation by less than 30% in all cases considered. This is demonstrated for gate oxides with widely varying ΔVot and ΔVit, and for parasitic field oxides. Preliminary results suggest that n-channel MOS ΔVot annealing and ΔVit buildup following switched-bias irradiation and through switched-bias annealing also may be predicted with less than 30% error. P-channel MOS response at high frequencies (> 1 kHz) is more difficult to predict. However, p-channel response only improves with bias switching during irradiation, so this does not cause problems for predicting the worst-case radiation response of MOS circuits or hardness assurance testing. © 1990 IEEE